S95. DIFFERENCES IN LIFETIME PATTERNS OF PSYCHOSTIMULANTS AND THEIR IMPACT ON THE PROPORTION OF PATIENTS WITH FIRST-EPISODE PSYCHOSIS ATTRIBUTABLE TO PSYCHOSTIMULANTS USE ACROSS EUROPE

Abstract Background Substance use may be a risk factor for the onset of schizophrenia. Almost 50 % of people with first episode psychosis (FEP) have a history of cannabis or alcohol use. Smaller but significant proportions of this population have a history of psychostimulants (PS) use. Cross-sectional studies have shown a link between recreational and regular use of PS and psychotic symptoms, particularly among individuals with PS dependence, that usually revert after drug withdrawal. Nevertheless, some PS users suffer not just spontaneous relapse of the symptoms but also persistent psychosis in the absence of the drug. European data are not available for a large sample of the prevalence of consumption and its relation to the severity of symptoms in FEP. For this purpose, we described the differences in patterns of use of PS current and lifetime between FEP and healthy controls (HC) and their impact on the severity of the clinical symptomatology. Methods This analysis is based on data from the case-control study work package of the EUropean network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI), which took part between 2010 and 2015 across six countries. 901 FEP patients (M age=30.76, SD= 10.51; 38.1% females) and 1235 HC (M=36.15, SD=13.30; 53% females) were included in the present case-control study. Data related to amphetamine use were obtained through CEQEU-GEI. To assess psychopathology the OPerational CRITeria (OPCRIT) system was used. Group comparisons were made using t-test or Chi square, and ANCOVA or logistic regression controlling for age, sex and cannabis use when appropriate. Results FEP subjects displayed a trend for higher use of PS in the last year (B=-0.18, p= 0.055: 81 (9%) FEP and 56 (4.5%)) and a significant higher lifetime use (Chi2= 37.33, p<0.001: 196 (21.8%) FEP and 149 (12.1%) HC) than HC, but the frequency of PS use did not differ between groups. Lifetime FEP PS-users showed higher scores, thus is, more severe symptoms in the Mania (t= -3.69, p< 0.001) and the general (t= -3.47, p= 0.001) factors compared to FEP non-PS-users. Current FEP PS-users showed higher scores in the Mania factor (t= -2.52, p= 0.012) than FEP non-PS-users. However, these results were not significant when the comparisons were adjusted for age, sex and cannabis use. FEP PS-users displayed lower scores than the non-users in the negative factor both in the last year (t= 2.10, p= 0.038 and: F1,866= 4.27, p= 0.039 when adjusted for age, sex and cannabis use) and lifetime (t= 1.99, p= 0.046 and F1,869= 1.37, p= 0.243 when adjusted for age, sex and cannabis use). Discussion As previous studies, we confirmed the higher rates of PS use in FEP than HC in a European study with a big sample. PS use was related to severity of clinical symptomatology. PS-users presented more severe general symptoms and, specifically, in the mania factor. Otherwise, FEP non-PS-user showed higher scores in the negative factor which might be related to the usual course of the psychosis without exposure to PS use.